why replace subfloor?
with what, plywood or concrete board?
fyi tiles crack under washer/dryer easily, plan accordingly

subfloor is easy to replace, but a bitch to remove
i spliced in a few water damage spots when doing my parents floor, it wasnt too bad at all under the carpet and whatnot
but next to their tub was a bitch, all the particleboard was waterlogged and corroded to shit and not flat at all so all the tiles were cracked
replaced with concrete and tiled over, needs to be redone again when new tub goes in soon, was just a temp fix a few yrs ago

pics?